Memory

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Memory

Types of Memory

Enhancing Memory

Memory researchers certainly haven’t forgotten Hermann Ebbinghaus, the
first person to do scientific studies of forgetting, using himself as a subject. He spent a lot
of time memorizing endless lists of nonsense syllables and then testing himself to see whether
he remembered them. He found that he forgot most of what he learned during the first few hours
after learning it.

Later researchers have found that forgetting doesn’t always occur that
quickly. Meaningful information fades more slowly than nonsense syllables. The rate at which
people forget or retain information also depends on what method is used to measure forgetting
and retention. Retention is the proportion of learned information that is retained
or remembered—the flip side of forgetting.

Forgetting Curve

A forgetting curve is a graph that shows how quickly learned information is
forgotten over time. Ebbinghaus made use of forgetting curves to chart his research on
memory.

Measures of Forgetting and Retention

Researchers measure forgetting and retention in three different ways: recall,
recognition, and relearning.

Recall

Recall is remembering without any external cues. For example, essay
questions test recall of knowledge because nothing on a blank sheet of paper will jog the
memory.

Recognition

Recognition is identifying learned information using external cues. For
example, true or false questions and multiple-choice questions test recognition because the
previously learned information is there on the page, along with other options. In general,
recognition is easier than recall.

Relearning

When using the relearning method to measure retention, a researcher
might ask a subject to memorize a long grocery list. She might measure how long he has to
practice before he remembers every item. Suppose it takes him ten minutes. On another day, she
gives him the same list again and measures how much time he takes to relearn the list. Suppose
he now learns it in five minutes. He has saved five minutes of learning time, or 50 percent of
the original time it took him to learn it. His savings score of 50 percent indicates that he
retained 50 percent of the information he learned the first time.

Causes of Forgetting

Everyone forgets things. There are six main reasons for forgetting: ineffective
encoding, decay, interference, retrieval failure, motivated forgetting, and physical injury or
trauma.

Ineffective Encoding

The way information is encoded affects the ability to remember it.
Processing information at a deeper level makes it harder to forget. If a student thinks about
the meaning of the concepts in her textbook rather than just reading them, she’ll remember
them better when the final exam comes around. If the information is not encoded properly—such
as if the student simply skims over the textbook while paying more attention to the TV—it is
more likely to be forgotten.

Decay

According to decay theory, memory fades with time. Decay
explains the loss of memories from sensory and short-term memory. However, loss of long-term
memories does not seem to depend on how much time has gone by since the information was
learned. People might easily remember their first day in junior high school but completely
forget what they learned in class last Tuesday.

Interference

Interference theory has a better account of why people lose
long-term memories. According to this theory, people forget information because of
interference from other learned information. There are two types of interference:
retroactive and proactive.

Retrieval Failure

Forgetting may also result from failure to retrieve information in
memory, such as if the wrong sort of retrieval cue is used. For example, Dan may
not be able to remember the name of his fifth-grade teacher. However, the teacher’s name might
suddenly pop into Dan’s head if he visits his old grade school and sees his fifth-grade
classroom. The classroom would then be acting as a context cue for retrieving the memory of
his teacher’s name.

Motivated Forgetting

Psychologist Sigmund Freud proposed that people forget because they push
unpleasant or intolerable thoughts and feelings deep into their unconscious. He called this
phenomenon repression. The idea that people forget things they don’t want to
remember is also called motivated forgetting or psychogenic amnesia.

Physical Injury or Trauma

Anterograde amnesia is the inability to remember events that occur after
an injury or traumatic event. Retrograde amnesia is the inability to remember
events that occurred before an injury or traumatic event.